(a) Technical Field of the Invention
The present invention generally relates to collapsible umbrellas and, more particularly, to the lower nest structure of collapsible umbrellas for opening and closing collapsible umbrellas.
(b) Description of the Prior Art
Conventionally, a collapsible umbrella contains a central shaft, an upper nest fixedly attached to a top end of the central shaft, a lower nest sliding along the central shaft, and a rib structure whose ribs are connected to both the upper and lower nests. As such, pushing or pulling the lower nest up or down would force the ribs of the rib structure to expand or retract and the collapsible umbrella is thereby opened or closed.
To maintain the umbrella in an open configuration, a positioning mechanism must be supplied to prevent the lower nest from sliding downward.
A conventional positioning mechanism is a resilient stopper extended from the inside of the central shaft. When the umbrella is open, the stopper is beneath the lower rest to prevent it from moving downward. To close the umbrella, the stopper is pressed into the central shaft so that the lower nest could pass the stopper and slide downward.
Using the resilient stopper as a positioning mechanism for the lower nest has a number of disadvantages. First, the resilient stopper is configured inside and extends out of the central shaft. The installation of the resilient stopper is not quite convenient. Secondly, the resilient stopper is usually configured as a blade. It is quite uncomfortable for a user to operate the resilient stopper to close the umbrella. Thirdly and most importantly, when the resilient stopper is pressed to make way for the lower nest, the lower nest would drop very quickly due to the retraction force of the rib structure, a user could easily get hurt if his or her finger is trapped between the resilient stopper and the lower nest.